He cited data from two trials which have shown diets like the WFPBD, which restricts animal protein, animal fat, omega-6 PUFAs, dairy, emulsifiers and food additives while providing dietary fibre can bring improvements in people with Crohn’s in just six weeks.

Patients in the trials obtained 50% of caloric intake from an enteral formula (an artificial ‘complete nutrition’ product) and the remaining 50% from a WFPBD.

Desmond noted that people with newly diagnosed Crohn’s, in addition to people with an established and ‘difficult-to-treat’ condition, showed complete remission rates of 62% and 71% while significant clinical improvements of 90% and 79% were seen.

Even more remarkably, according to Desmond, out of 18 patients who refused to take the enteral formula and instead pursued a WFPBD solely, 14 achieved complete remission.

Evidence also suggests that CD remission may be maintained over the longer-term even if only a semi-vegetarian diet is followed, he said.

Fibre – good for Crohn’s?​

A low-fibre diet has always been the standard advice for Crohn’s patients, with the underlying rationale of avoiding flare-ups. Yet many studies showed no benefit, or even harmful effects of this regime, Desmond pointed out.

Although limited in size and numbers of trials, evidence exists to show that soluble fibre can in fact induce improvements in Crohn’s, he said – adding that a small trial of CD patients given a breakfast high in soluble fibre reported improvements in many symptoms – including improved quality of life.

“We know that soluble fibre reduces inflammation of the gut. We know that fibre actually helps maintain the integrity of the epithelial barrier,”​ said Desmond.

Animal fats and proteins​

Observational data has shown that those who consume the highest levels of animal protein carry the highest risk of developing IBD, noted the expert.

One study also showed that other risk factors for IBD include a higher ratio of animal: vegetable protein intake, higher omega-6: omega-3 ratio and higher iron intake, Desmond added.

Strong evidence also exists that dairy consumption may be a culprit in bowel disorders, he noted.

“A high milk-fat diet can induce or exacerbate Crohn’s disease or colitis by multiple mechanisms.”​

These mechanisms include reduced mucus layer, higher gut permeability, increased production of inflammatory molecules, greater bacterial penetration of the gut wall and unfavourable changes to the gut bacteria composition, he said.

Evidence-based advice​

According to Desmond, f​oods to include in diets include: soluble fibre (oats, psyllium, pulses); insoluble fibre (whole grains and nuts, as tolerated); fruit and vegetables, sources of omega-3 fatty acids.

He added that there is no strong evidence for gluten-free or low FODMAP diets, or to exclude soy or yeast.

However, items that should be avoided are meat, dairy fats and cheese; large quantities of fruit juice and juices with high-fructose content; food emulsifiers and maltodextrin.

“When I see my patients with IBD or Crohn’s this is the evidence-based advice I give them​,” said Desmond.